Fall in zone 4bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 57645 (Morristown, SD)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Pretty Rock, ND (20 miles away).
- Average last spring frostMay 2050% chance of a 32°F freeze after this date
- Average first fall frostSep 2350% chance of a 32°F freeze by this date
- Growing season (frost-free)124 daysmedian, 32°F threshold
- USDA hardiness zone4b-25 to -20°F avg. coldest night
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This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
No soil station with a fresh reading within 62 miles.
4-inch depth
No soil station with a fresh reading within 62 miles.
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 57645 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
No soil reading near this ZIP. Typical extension timing for your region: spring mid-April to early May.
Fertilizer window
Lawn region: North (cool-season). Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | May 7 |
| 50% (the "average" last frost) | May 20 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 3 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Sep 8 |
| 50% (the "average" first frost) | Sep 23 |
| 90% (late: most years have frozen by now) | Oct 5 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 31 | Sep 11 |
| 32°F (freeze) | May 20 | Sep 23 |
| 28°F (hard freeze) | May 9 | Oct 2 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 57645
Dates count from your average last spring frost (May 20) and first fall frost (Sep 23). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Mar 25–Apr 8 | May 27–Jun 10 (transplant) | – |
| Pepper (sweet and hot) | Mar 11–25 | Jun 3–17 (transplant) | – |
| Eggplant | Mar 11–25 | Jun 3–17 (transplant) | – |
| Tomatillo | Mar 25–Apr 8 | May 27–Jun 10 (transplant) | – |
| Lettuce | Mar 25–Apr 8 | Apr 29–May 20 (transplant) Apr 22–Jun 3 (sow outdoors) | Jul 29–Aug 19 (transplant) Jul 15–Aug 12 (sowing) |
| Spinach | – | Apr 8–29 (sow outdoors) | Jul 29–Aug 19 (sowing) |
| Kale | Mar 25–Apr 8 | Apr 22–May 6 (transplant) Apr 22–May 6 (sow outdoors) | Jul 1–29 (transplant) Jun 17–Jul 15 (sowing) |
| Collards | Mar 25–Apr 8 | Apr 22–May 20 (transplant) Apr 22–May 20 (sow outdoors) | Jul 1–29 (transplant) Jun 17–Jul 15 (sowing) |
| Broccoli | Mar 11–25 | Apr 22–May 6 (transplant) | Jun 17–Jul 15 (transplant) |
| Cabbage | Mar 11–25 | Apr 22–May 6 (transplant) | Jun 17–Jul 15 (transplant) |
| Cauliflower | Mar 11–25 | May 6–20 (transplant) | Jun 17–Jul 15 (transplant) |
| Brussels sprouts | Feb 25–Mar 11 | Apr 22–May 6 (transplant) | Jun 3–24 (transplant) |
| Kohlrabi | Mar 25–Apr 8 | Apr 22–May 6 (transplant) Apr 22–May 6 (sow outdoors) | Jul 15–29 (sowing) |
| Bok choy / Asian greens | – | Apr 22–May 6 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Arugula | – | Apr 22–May 20 (sow outdoors) | Jul 29–Aug 26 (sowing) |
| Mustard greens | – | Apr 22–May 13 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Swiss chard | Apr 8–22 | May 6–27 (transplant) May 6–Jun 3 (sow outdoors) | Jul 15–29 (sowing) |
| Beet | – | Apr 22–May 20 (sow outdoors) | Jul 15–29 (sowing) |
| Carrot | – | Apr 29–May 27 (sow outdoors) | Jul 1–15 (sowing) |
| Radish | – | Apr 15–May 27 (sow outdoors) | Aug 12–26 (sowing) |
| Turnip | – | Apr 22–May 13 (sow outdoors) | Jul 15–29 (sowing) |
| Parsnip | – | Apr 29–May 20 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 25–Apr 22 (sow outdoors) | Jul 1–15 (sowing) |
| Onion (bulbing) | Feb 25–Mar 11 | Apr 8–22 (transplant) | – |
| Green onion / scallion | – | Apr 8–May 6 (sow outdoors) | Jul 15–29 (sowing) |
| Leek | Feb 25–Mar 11 | Apr 22–May 6 (transplant) | – |
| Garlic | – | – | Aug 12–Sep 9 (sowing) |
| Shallot | – | Apr 8–22 (transplant) | Aug 12–Sep 9 (sowing) |
| Potato | – | Apr 22–May 6 (transplant) | Jun 3–17 (transplant) |
| Sweet potato | – | Jun 10–24 (transplant) | – |
| Sweet corn | – | May 27–Jun 10 (sow outdoors) | – |
| Bean, bush (snap) | – | May 27–Jun 10 (sow outdoors) | – |
| Bean, pole | – | May 27–Jun 10 (sow outdoors) | – |
| Lima bean | – | Jun 3–17 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 10–Jul 1 (sow outdoors) | – |
| Cucumber | Apr 22–29 | May 27–Jun 10 (transplant) May 27–Jun 10 (sow outdoors) | – |
| Summer squash / zucchini | Apr 22–29 | May 27–Jun 10 (transplant) May 27–Jun 10 (sow outdoors) | – |
| Winter squash | Apr 22–29 | May 27–Jun 10 (transplant) May 27–Jun 10 (sow outdoors) | – |
| Pumpkin | – | May 27–Jun 10 (sow outdoors) | – |
| Watermelon | Apr 22–29 | Jun 3–17 (transplant) Jun 3–17 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 22–29 | Jun 3–17 (transplant) Jun 3–17 (sow outdoors) | – |
| Okra | Apr 8–22 | Jun 3–17 (transplant) Jun 3–17 (sow outdoors) | – |
| Celery | Feb 25–Mar 11 | May 27–Jun 3 (transplant) | – |
| Basil | Apr 8–22 | May 27–Jun 10 (transplant) May 27–Jun 10 (sow outdoors) | – |
| Cilantro | – | May 6–Jun 3 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Parsley | Mar 11–25 | May 6–20 (transplant) Apr 29–May 20 (sow outdoors) | – |
| Dill | – | May 20–Jun 3 (sow outdoors) | Jul 29–Aug 12 (sowing) |
| Sunflower | – | May 20–Jun 3 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 22–May 6 (transplant) | – |
| Rhubarb (crowns) | – | Apr 22–May 6 (transplant) | – |
| Strawberry (plants) | – | Apr 22–May 6 (transplant) | Jul 15–Aug 12 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Pretty Rock, ND (NOAA GHCN-Daily ID USC00327311), elevation 2,480 ft, 19.7 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Lemmon, SD | 21 mi | May 10 | Sep 30 |
| Mc Intosh 6 SE, SD | 22 mi | May 9 | Sep 30 |
| Shadehill Rsvr, SD | 31 mi | May 16 | Sep 24 |
The average last-frost dates of these stations span 11 days, a rough guide to local variation. See data sources & methods.
Frost questions for 57645
When is the last frost in 57645?
The average (50% chance) last spring freeze of 32°F for ZIP 57645 is May 20. For a more cautious planting date, use June 3, when only 1 year in 10 still sees a later freeze.
When is the first frost in 57645?
The average first fall freeze is September 23. In 1 year in 10 it comes by September 8.
What hardiness zone is 57645?
ZIP 57645 is in USDA zone 4b (-25 to -20°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 57645 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
57660 57634 57641 McIntosh 57638 Lemmon 58529 Carson 57659 58564 Raleigh 57621 Bullhead
Other ZIP codes in Corson County
57621 57633 57634 57639 57641 57642 57657 57658 57659 57660 All Corson County frost dates · South Dakota frost dates
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Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
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Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.